Compilation of Design Guideline for Piled Raft

Foundation

by

Nur Hayati Binti Abdul Rahman

Dissertation submitted in partial fulfillment of

the requirements for the

Bachelor of Engineering (Hons)

(Civil Engineering)

JANUARY 2008

Universiti Teknologi PETRONAS

Bandar Seri Iskandar

31750 Tronoh

Perak Darul Ridzuan

o\pproved by,

CERTIFICATION OF APPROVAL

Compilation Design Guideline for Piled Raft Foundation

by

Nur Hayati Binti Abdul Rahman

A project dissertation submitted to the

Civil Engineering Programme

Universiti Teknologi PETRONAS

in partial fulfilment of the requirement for the

BACHELOR OF ENGINEERING (Hons)

(CIVIL ENGINEERING)

:AP Dr lndra Sati Hamonangan Harahap)

UNIVERSITI TEKNOLOGI PETRONAS

TRONOH, PERAK

JANUARY 2008

CERTIFICATION OF ORIGINALITY

This is to certify that I am responsible for the work submitted in this project, that the original

work is my own except as specified in the references and acknowledgements, and that the

original work contained herein have not been undertaken or done by unspecified sources or

persons.

NUR HA YATI BINTI ABDUL RAHMAN

ii

TABLE OF CONTENT

CERTIFICATION............................................................................. i

TABLE OF CONTENT...................................................................... iii

ABSTRACT..................................................................................... vi

ACKNOWLEDGEMENT........................................................................................... vii

CHAPTER 1: INTRODUCTION........................................................... 1

1.1: Background study............................................................... 3

1.2: Problem statement.............................................................. 4

1.3: Objectives and scope ofworks................................................ 5

CHAPTER 2: LITERATURE REVIEW/ PROJECT OVERVIEW............... 6

2.1: Introduction.................................................................... 6

2.2: Design Issues.................................................................. 7

2.3: Design process.......................................................................... 8

2.4: Classification of methods of analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... 8

2.5: Piled raft interactions........................................................ 9

2.6: Formulas used in design guideline......................................... 9

2.6.1: Number of piles required and spacing.............................. 9

2.6.2: Bearing capacity of piled raft....................................... 11

2.6.3: Raft stiffuess. .. ...... ...... ...... ....... ........ ... ....... .. .... ...... 13

2.6.4: Pile group stiffuess... .. .... ....... ........ ....... ........ ...... ...... 14

2.6.5: Differential settlement................................................ 16

2.6.6: Load distribution between raft and pile groups................... 18

iii

CHAPTER 3: METHODOLOGY AND PROJECT WORKS......................... 19

3.1: Research......................................................................... 19

3.2: Compiling....................................................................... 19

3.3: Development of spreadsheet.................................................. 20

CHAPTER 4: RESULT & DISCUSSION...................................................... 21

4.1: Result............................................................................. 21

4.2: Discussion....................................................................... 22

4.2.1: Design approach........................................................ 23

4.2.2: Flow chart of design procedure for pile raft foundation........... 25

4.2.3: Subsurface Investigation, Field Test and Laboratory Test......... 27

4.2.4: Soil data.................................................................. 30

4.2.5: Pile and raft data........................................................ 33

4.2.6: Calculation............................................................... 34

4.2. 7: Analysis.................................................................. 35

CHAPTER 5: CONCLUSION/RECOMMENDATIONS.............................. 37

5.1: Conclusion....................................................................... 37

5.2: Recommendations ............................................................. . 37

REFERENCES.................................................................................. 39

APPENDICES................................................................................... 41

iv

TABLE OF FIGURES

Figure 1.1: Illustrations of KLCC' s foundation 2

Figure 2.1: Coefficients Bz, Bx, and Bljf for rectangular footings( after Richard et 14

al, 1970)

Figure 2.2: Variation of normalised differential settlement with raft-soil stiffuess 17

ratio, Krs

Figure 4.1: Flowchart of design procedure for piled raft

Figure 4.2: Load transfer in friction pile

LIST OF TABLES

Table 4.1: Representative values of Young's modulus, E,

Table 4.2: Representative values of Poisson's ratio of soil, v,

Table 4.3: Representative values of Shear modulus of soil, G,

Table 4.4: Undrained shear strength, Cu classification

v

27

35

30

31

32

33

ABSTARCT

Piled raft foundation is being used widely nowadays, due to its advantages in

foundation construction. Piled raft can be used for different cases, such as settlement

reducers, and improving bearing capacity of shallow foundation. Piled raft foundation is

one of the complex foundation, because it has to consider varies of aspects and

consideration. In UTP, especially for civil engineering students, this guideline will help

them to learn about piled raft foundation. In this project, one design guidelines will be

compiled to help students and others user, in learning the piled raft design. The design

guideline will focus on the used of piled raft as settlement reducer for development on

soft soil area, where friction pile is used in the design and it will be a "floating" piled

raft. In others words, the pile group are not driven until reached the hard layer, but its

length will cut at certain depth. Simple calculation methods introduced by various

researchers are used in the design calculation, such as Randolph, Poulos and etc. The

guideline coverage is ranging from the early staged of soil investigation until design

analysis. All the information are collected from the available guideline produced by

other parties such as geotechnical consultant, reference books, journals and articles. At

the end of this project, one compilation of piled raft design will be documented and

together with a spreadsheet, with the objective to assist students in design calculation.

Keywords: Piled raft, settlement reducers, friction pile, negative skin friction, total

settlement, differential settlement, load sharing between raft and piles.

vi

ACKNOWLEDMENT

I wish to express thanks to my supervisor, AP Dr Indra Sati Hamonangan

Harahap for helping me in this compilation of design guideline for piled raft foundation.

His assistance helps more in completing this guideline.

I want acknowledge and thank to G&P Geotechnics Sdn. Bhd for making this

project possible. Their contribution range from providing necessary information

regarded piled raft design such as articles, journals and also a design guideline for piled

raft foundation as my references. To my friends, whose also give some contribution

along the project, special thanks to them especially to Mohd Zulhihni Bin Mokhtar.

Also not to be forgotten, thank you to anyone that have give contribution in this

project directly or indirectly.

vii

CHAPTER I

INTRODUCTION

Piled raft foundation is designed to minimize both total settlement and

differential settlement. It also can be used to improve bearing capacity of a shallow

foundation and for reducing the internal stress and bending moment within the raft.

The used of piled raft in foundation construction was already implemented a few

decades ago in other countries for example Germany. In Germany, piled rafts were first

used in the settlement-active Frankfurt Clay, with the intention to reduce the settlement

and the risks of building tilting.

In Malaysia perspective, many Malaysian didn't know that Kuala Lumpur City

Center (KLCC) is supported by piled raft foundation with different length of piles

varying from 60 - 115 meters length. According to original location of KLCC, tower

one is located at limestone area and tower two was at Kenny Hill soil area, but after a

few construction issues, both tower were moving to Kenny Hill soil area. Due to the

greater load from the two towers and the soil condition, settlement and tilting of the

structures were become main consideration of the construction. Therefore, piled raft

with different length of pile is implemented. See Figure 1.1 for the illustrations of

KLCC's foundation.

I